/*  -*-  mode: c; tab-width: 4; indent-tabs-mode: t; c-basic-offset: 4; coding: utf-8  -*-  */
/**
  ******************************************************************************
  * @file    EEPROM_Emulation/src/eeprom.c
  * @author  MCD Application Team
  * @version V1.0.0
  * @date    10-October-2011
  * @brief   This file provides all the EEPROM emulation firmware functions.
  ******************************************************************************
  * @attention
  *
  * THE PRESENT FIRMWARE WHICH IS FOR GUIDANCE ONLY AIMS AT PROVIDING CUSTOMERS
  * WITH CODING INFORMATION REGARDING THEIR PRODUCTS IN ORDER FOR THEM TO SAVE
  * TIME. AS A RESULT, STMICROELECTRONICS SHALL NOT BE HELD LIABLE FOR ANY
  * DIRECT, INDIRECT OR CONSEQUENTIAL DAMAGES WITH RESPECT TO ANY CLAIMS ARISING
  * FROM THE CONTENT OF SUCH FIRMWARE AND/OR THE USE MADE BY CUSTOMERS OF THE
  * CODING INFORMATION CONTAINED HEREIN IN CONNECTION WITH THEIR PRODUCTS.
  *
  * <h2><center>&copy; COPYRIGHT 2011 STMicroelectronics</center></h2>
  ******************************************************************************
  */

/** @addtogroup EEPROM_Emulation
  * @{
  */


// Common
#include "mchf_board.h"

/* Includes ------------------------------------------------------------------*/
#include "eeprom.h"

/* Private typedef -----------------------------------------------------------*/
/* Private define ------------------------------------------------------------*/
#define VAR_ADDR_START  (0xAA01)
// this value is required to remain unchanged in order to not break existing mcHF flash configuration
// readings. It is otherwise just an arbitrary number.

/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/

/* Global variable used to store variable value in read sequence */
static uint16_t DataVar = 0;

/* Virtual address defined by the user: 0xFFFF value is prohibited */

/* Private function prototypes -----------------------------------------------*/
/* Private functions ---------------------------------------------------------*/
static FLASH_Status Flash_Format(void);
static uint16_t Flash_FindValidPage(uint8_t Operation);
static uint16_t Flash_VerifyPageFullWriteVariable(uint16_t VirtAddress, uint16_t Data);
static uint16_t Flash_PageTransfer(uint16_t VirtAddress, uint16_t Data);

/**
 * This code encapsulates the former direct use of mapping table
 * Since we never used the mapping table except for mapping to an offset,
 * we now use code to convert the id (start from 0) to addresses  (starting from VAR_ADDR_START)
 * This allows full backward compatibility of stored settings.
 */
uint16_t Flash_GetVirtAddrForId(uint16_t id) {
    return VAR_ADDR_START + id;
}

/**
  * @brief  Restore the pages to a known good state in case of page's status
  *   corruption after a power loss.
  * @param  None.
  * @retval - Flash error code: on write Flash error
  *         - FLASH_COMPLETE: on success
  */
uint16_t Flash_InitA(void)
{
    uint16_t PageStatus0, PageStatus1;
    uint16_t VarIdx = 0;
    uint16_t EepromStatus = 0, ReadStatus = 0;
    int16_t x = -1;
    uint16_t  FlashStatus;

    /* Get Page0 status */
    PageStatus0 = (*(__IO uint16_t*)PAGE0_BASE_ADDRESS);
    /* Get Page1 status */
    PageStatus1 = (*(__IO uint16_t*)PAGE1_BASE_ADDRESS);

    /* Check for invalid header states and repair if necessary */
    switch (PageStatus0)
    {
    case ERASED:
        if (PageStatus1 == VALID_PAGE) /* Page0 erased, Page1 valid */
        {
            /* Erase Page0 */
            FlashStatus = FLASH_EraseSector(PAGE0_ID,VOLTAGE_RANGE);
            /* If erase operation was failed, a Flash error code is returned */
            if (FlashStatus != FLASH_COMPLETE)
            {
                return FlashStatus;
            }
        }
        else if (PageStatus1 == RECEIVE_DATA) /* Page0 erased, Page1 receive */
        {
            /* Erase Page0 */
            FlashStatus = FLASH_EraseSector(PAGE0_ID, VOLTAGE_RANGE);
            /* If erase operation was failed, a Flash error code is returned */
            if (FlashStatus != FLASH_COMPLETE)
            {
                return FlashStatus;
            }
            /* Mark Page1 as valid */
            FlashStatus = FLASH_ProgramHalfWord(PAGE1_BASE_ADDRESS, VALID_PAGE);
            /* If program operation was failed, a Flash error code is returned */
            if (FlashStatus != FLASH_COMPLETE)
            {
                return FlashStatus;
            }
        }
        else /* First EEPROM access (Page0&1 are erased) or invalid state -> format EEPROM */
        {
            /* Erase both Page0 and Page1 and set Page0 as valid page */
            FlashStatus = Flash_Format();
            /* If erase/program operation was failed, a Flash error code is returned */
            if (FlashStatus != FLASH_COMPLETE)
            {
                return FlashStatus;
            }
        }
        break;

    case RECEIVE_DATA:
        if (PageStatus1 == VALID_PAGE) /* Page0 receive, Page1 valid */
        {
            /* Transfer data from Page1 to Page0 */
            for (VarIdx = 0; VarIdx < NB_OF_VAR; VarIdx++)
            {
                if (( *(__IO uint16_t*)(PAGE0_BASE_ADDRESS + 6)) == Flash_GetVirtAddrForId(VarIdx))
                {
                    x = VarIdx;
                }
                if (VarIdx != x)
                {
                    /* Read the last variables' updates */
                    ReadStatus = Flash_ReadVariable(Flash_GetVirtAddrForId(VarIdx), &DataVar);
                    /* In case variable corresponding to the virtual address was found */
                    if (ReadStatus != 0x1)
                    {
                        /* Transfer the variable to the Page0 */
                        EepromStatus = Flash_VerifyPageFullWriteVariable(Flash_GetVirtAddrForId(VarIdx), DataVar);
                        /* If program operation was failed, a Flash error code is returned */
                        if (EepromStatus != FLASH_COMPLETE)
                        {
                            return EepromStatus;
                        }
                    }
                }
            }
            /* Mark Page0 as valid */
            FlashStatus = FLASH_ProgramHalfWord(PAGE0_BASE_ADDRESS, VALID_PAGE);
            /* If program operation was failed, a Flash error code is returned */
            if (FlashStatus != FLASH_COMPLETE)
            {
                return FlashStatus;
            }
            /* Erase Page1 */
            FlashStatus = FLASH_EraseSector(PAGE1_ID, VOLTAGE_RANGE);
            /* If erase operation was failed, a Flash error code is returned */
            if (FlashStatus != FLASH_COMPLETE)
            {
                return FlashStatus;
            }
        }
        else if (PageStatus1 == ERASED) /* Page0 receive, Page1 erased */
        {
            /* Erase Page1 */
            FlashStatus = FLASH_EraseSector(PAGE1_ID, VOLTAGE_RANGE);
            /* If erase operation was failed, a Flash error code is returned */
            if (FlashStatus != FLASH_COMPLETE)
            {
                return FlashStatus;
            }
            /* Mark Page0 as valid */
            FlashStatus = FLASH_ProgramHalfWord(PAGE0_BASE_ADDRESS, VALID_PAGE);
            /* If program operation was failed, a Flash error code is returned */
            if (FlashStatus != FLASH_COMPLETE)
            {
                return FlashStatus;
            }
        }
        else /* Invalid state -> format eeprom */
        {
            /* Erase both Page0 and Page1 and set Page0 as valid page */
            FlashStatus = Flash_Format();
            /* If erase/program operation was failed, a Flash error code is returned */
            if (FlashStatus != FLASH_COMPLETE)
            {
                return FlashStatus;
            }
        }
        break;

    case VALID_PAGE:
        if (PageStatus1 == VALID_PAGE) /* Invalid state -> format eeprom */
        {
            /* Erase both Page0 and Page1 and set Page0 as valid page */
            FlashStatus = Flash_Format();
            /* If erase/program operation was failed, a Flash error code is returned */
            if (FlashStatus != FLASH_COMPLETE)
            {
                return FlashStatus;
            }
        }
        else if (PageStatus1 == ERASED) /* Page0 valid, Page1 erased */
        {
            /* Erase Page1 */
            FlashStatus = FLASH_EraseSector(PAGE1_ID, VOLTAGE_RANGE);
            /* If erase operation was failed, a Flash error code is returned */
            if (FlashStatus != FLASH_COMPLETE)
            {
                return FlashStatus;
            }
        }
        else /* Page0 valid, Page1 receive */
        {
            /* Transfer data from Page0 to Page1 */
            for (VarIdx = 0; VarIdx < NB_OF_VAR; VarIdx++)
            {
                if ((*(__IO uint16_t*)(PAGE1_BASE_ADDRESS + 6)) == Flash_GetVirtAddrForId(VarIdx))
                {
                    x = VarIdx;
                }
                if (VarIdx != x)
                {
                    /* Read the last variables' updates */
                    ReadStatus = Flash_ReadVariable(Flash_GetVirtAddrForId(VarIdx), &DataVar);
                    /* In case variable corresponding to the virtual address was found */
                    if (ReadStatus != 0x1)
                    {
                        /* Transfer the variable to the Page1 */
                        EepromStatus = Flash_VerifyPageFullWriteVariable(Flash_GetVirtAddrForId(VarIdx), DataVar);
                        /* If program operation was failed, a Flash error code is returned */
                        if (EepromStatus != FLASH_COMPLETE)
                        {
                            return EepromStatus;
                        }
                    }
                }
            }
            /* Mark Page1 as valid */
            FlashStatus = FLASH_ProgramHalfWord(PAGE1_BASE_ADDRESS, VALID_PAGE);
            /* If program operation was failed, a Flash error code is returned */
            if (FlashStatus != FLASH_COMPLETE)
            {
                return FlashStatus;
            }
            /* Erase Page0 */
            FlashStatus = FLASH_EraseSector(PAGE0_ID, VOLTAGE_RANGE);
            /* If erase operation was failed, a Flash error code is returned */
            if (FlashStatus != FLASH_COMPLETE)
            {
                return FlashStatus;
            }
        }
        break;

    default:  /* Any other state -> format eeprom */
        /* Erase both Page0 and Page1 and set Page0 as valid page */
        FlashStatus = Flash_Format();
        /* If erase/program operation was failed, a Flash error code is returned */
        if (FlashStatus != FLASH_COMPLETE)
        {
            return FlashStatus;
        }
        break;
    }

    return FLASH_COMPLETE;
}

// Proxy
uint16_t Flash_Init(void)
{
    uint16_t res;

    FLASH_Unlock();
    res = Flash_InitA();
    FLASH_Lock();

    return res;
}

/**
  * @brief  Returns the last stored variable data, if found, which correspond to
  *   the passed virtual address
  * @param  VirtAddress: Variable virtual address
  * @param  Data: Global variable contains the read variable value
  * @retval Success or error status:
  *           - 0: if variable was found
  *           - 1: if the variable was not found
  *           - NO_VALID_PAGE: if no valid page was found.
  */
uint16_t Flash_ReadVariable(uint16_t addr, uint16_t* value)
{
    uint16_t VirtAddress = Flash_GetVirtAddrForId(addr);
    uint16_t ValidPage;
    uint16_t AddressValue = 0x5555, ReadStatus = 1;
    uint32_t Address = EEPROM_START_ADDRESS, PageStartAddress = EEPROM_START_ADDRESS;

    /* Get active Page for read operation */
    ValidPage = Flash_FindValidPage(READ_FROM_VALID_PAGE);

    /* Check if there is no valid page */
    if (ValidPage == NO_VALID_PAGE)
    {
        return  NO_VALID_PAGE;
    }

    /* Get the valid Page start Address */
    PageStartAddress = (uint32_t)(EEPROM_START_ADDRESS + (uint32_t)(ValidPage * PAGE_SIZE));

    /* Get the valid Page end Address */
    Address = (uint32_t)((EEPROM_START_ADDRESS - 2) + (uint32_t)((1 + ValidPage) * PAGE_SIZE));

    /* Check each active page address starting from end */
    while (Address > (PageStartAddress + 2))
    {
        /* Get the current location content to be compared with virtual address */
        AddressValue = (*(__IO uint16_t*)Address);

        /* Compare the read address with the virtual address */
        if (AddressValue == VirtAddress)
        {
            /* Get content of Address-2 which is variable value */
            *value = (*(__IO uint16_t*)(Address - 2));

            /* In case variable value is read, reset ReadStatus flag */
            ReadStatus = 0;

            break;
        }
        else
        {
            /* Next address location */
            Address = Address - 4;
        }
    }

    /* Return ReadStatus value: (0: variable exist, 1: variable doesn't exist) */
    return ReadStatus;
}

/**
  * @brief  Writes/updates variable data in EEPROM if necessary.
  * @param  VirtAddress: Variable virtual address
  * @param  Data: 16 bit data to be written
  * @retval Success or error status:
  *           - FLASH_COMPLETE: on success
  *           - PAGE_FULL: if valid page is full
  *           - NO_VALID_PAGE: if no valid page was found
  *           - Flash error code: on write Flash error
  */
uint16_t Flash_UpdateVariable(uint16_t addr, uint16_t value)
{
    uint16_t DataRead = 0;
    uint16_t Status = 0;
    Status = Flash_ReadVariable(addr,&DataRead);
    // the variable was found and the data content is  equal to the new value
    // -> no need to write it again
    if (Status == 0 && DataRead == value)
    {
        Status = FLASH_COMPLETE;
    }
    else
    {
        Status = Flash_WriteVariable(addr, value);
    }
    return Status;
}

/**
  * @brief  Writes/updates variable data in EEPROM.
  * @param  VirtAddress: Variable virtual address
  * @param  Data: 16 bit data to be written
  * @retval Success or error status:
  *           - FLASH_COMPLETE: on success
  *           - PAGE_FULL: if valid page is full
  *           - NO_VALID_PAGE: if no valid page was found
  *           - Flash error code: on write Flash error
  */
uint16_t Flash_WriteVariable(uint16_t addr, uint16_t value)
{
    uint16_t Status = 0;
    uint16_t VirtAddress = Flash_GetVirtAddrForId(addr);

    FLASH_Unlock();

    /* Write the variable virtual address and value in the EEPROM */
    Status = Flash_VerifyPageFullWriteVariable(VirtAddress, value);

    /* In case the EEPROM active page is full */
    if (Status == PAGE_FULL)
    {
        /* Perform Page transfer */
        Status = Flash_PageTransfer(VirtAddress, value);
    }

    FLASH_Lock();

    /* Return last operation status */
    return Status;
}

/**
  * @brief  Erases PAGE and PAGE1 and writes VALID_PAGE header to PAGE
  * @param  None
  * @retval Status of the last operation (Flash write or erase) done during
  *         EEPROM formating
  */
static FLASH_Status Flash_Format(void)
{
    FLASH_Status FlashStatus;

    /* Erase Page0 */
    FlashStatus = FLASH_EraseSector(PAGE0_ID, VOLTAGE_RANGE);

    /* If erase operation was failed, a Flash error code is returned */
    if (FlashStatus != FLASH_COMPLETE)
    {
        return FlashStatus;
    }

    /* Set Page0 as valid page: Write VALID_PAGE at Page0 base address */
    FlashStatus = FLASH_ProgramHalfWord(PAGE0_BASE_ADDRESS, VALID_PAGE);

    /* If program operation was failed, a Flash error code is returned */
    if (FlashStatus != FLASH_COMPLETE)
    {
        return FlashStatus;
    }

    /* Erase Page1 */
    FlashStatus = FLASH_EraseSector(PAGE1_ID, VOLTAGE_RANGE);

    /* Return Page1 erase operation status */
    return FlashStatus;
}

/**
  * @brief  Find valid Page for write or read operation
  * @param  Operation: operation to achieve on the valid page.
  *   This parameter can be one of the following values:
  *     @arg READ_FROM_VALID_PAGE: read operation from valid page
  *     @arg WRITE_IN_VALID_PAGE: write operation from valid page
  * @retval Valid page number (PAGE or PAGE1) or NO_VALID_PAGE in case
  *   of no valid page was found
  */
static uint16_t Flash_FindValidPage(uint8_t Operation)
{
    uint16_t PageStatus0, PageStatus1;

    /* Get Page0 actual status */
    PageStatus0 = (*(__IO uint16_t*)PAGE0_BASE_ADDRESS);

    /* Get Page1 actual status */
    PageStatus1 = (*(__IO uint16_t*)PAGE1_BASE_ADDRESS);

    /* Write or read operation */
    switch (Operation)
    {
    case WRITE_IN_VALID_PAGE:   /* ---- Write operation ---- */
        if (PageStatus1 == VALID_PAGE)
        {
            /* Page0 receiving data */
            if (PageStatus0 == RECEIVE_DATA)
            {
                return PAGE0;         /* Page0 valid */
            }
            else
            {
                return PAGE1;         /* Page1 valid */
            }
        }
        else if (PageStatus0 == VALID_PAGE)
        {
            /* Page1 receiving data */
            if (PageStatus1 == RECEIVE_DATA)
            {
                return PAGE1;         /* Page1 valid */
            }
            else
            {
                return PAGE0;         /* Page0 valid */
            }
        }
        else
        {
            return NO_VALID_PAGE;   /* No valid Page */
        }

    case READ_FROM_VALID_PAGE:  /* ---- Read operation ---- */
        if (PageStatus0 == VALID_PAGE)
        {
            return PAGE0;           /* Page0 valid */
        }
        else if (PageStatus1 == VALID_PAGE)
        {
            return PAGE1;           /* Page1 valid */
        }
        else
        {
            return NO_VALID_PAGE ;  /* No valid Page */
        }

    default:
        return PAGE0;             /* Page0 valid */
    }
}

/**
  * @brief  Verify if active page is full and Writes variable in EEPROM.
  * @param  VirtAddress: 16 bit virtual address of the variable
  * @param  Data: 16 bit data to be written as variable value
  * @retval Success or error status:
  *           - FLASH_COMPLETE: on success
  *           - PAGE_FULL: if valid page is full
  *           - NO_VALID_PAGE: if no valid page was found
  *           - Flash error code: on write Flash error
  */
static uint16_t Flash_VerifyPageFullWriteVariable(uint16_t VirtAddress, uint16_t Data)
{
    FLASH_Status FlashStatus;
    uint16_t ValidPage;
    uint32_t Address = EEPROM_START_ADDRESS, PageEndAddress = EEPROM_START_ADDRESS+PAGE_SIZE;

    /* Get valid Page for write operation */
    ValidPage = Flash_FindValidPage(WRITE_IN_VALID_PAGE);

    /* Check if there is no valid page */
    if (ValidPage == NO_VALID_PAGE)
    {
        return  NO_VALID_PAGE;
    }

    /* Get the valid Page start Address */
    Address = (uint32_t)(EEPROM_START_ADDRESS + (uint32_t)(ValidPage * PAGE_SIZE));

    /* Get the valid Page end Address */
    PageEndAddress = (uint32_t)((EEPROM_START_ADDRESS - 2) + (uint32_t)((1 + ValidPage) * PAGE_SIZE));

    /* Check each active page address starting from begining */
    while (Address < PageEndAddress)
    {
        /* Verify if Address and Address+2 contents are 0xFFFFFFFF */
        if ((*(__IO uint32_t*)Address) == 0xFFFFFFFF)
        {
            /* Set variable data */
            FlashStatus = FLASH_ProgramHalfWord(Address, Data);
            /* If program operation was failed, a Flash error code is returned */
            if (FlashStatus != FLASH_COMPLETE)
            {
                return FlashStatus;
            }
            /* Set variable virtual address */
            FlashStatus = FLASH_ProgramHalfWord(Address + 2, VirtAddress);
            /* Return program operation status */
            return FlashStatus;
        }
        else
        {
            /* Next address location */
            Address = Address + 4;
        }
    }

    /* Return PAGE_FULL in case the valid page is full */
    return PAGE_FULL;
}

/**
  * @brief  Transfers last updated variables data from the full Page to
  *   an empty one.
  * @param  VirtAddress: 16 bit virtual address of the variable
  * @param  Data: 16 bit data to be written as variable value
  * @retval Success or error status:
  *           - FLASH_COMPLETE: on success
  *           - PAGE_FULL: if valid page is full
  *           - NO_VALID_PAGE: if no valid page was found
  *           - Flash error code: on write Flash error
  */
static uint16_t Flash_PageTransfer(uint16_t VirtAddress, uint16_t Data)
{
    FLASH_Status FlashStatus;
    uint32_t NewPageAddress = EEPROM_START_ADDRESS;
    uint16_t OldPageId=0;
    uint16_t ValidPage;
    uint16_t VarIdx = 0, EepromStatus = 0, ReadStatus = 0;

    /* Get active Page for read operation */
    ValidPage = Flash_FindValidPage(READ_FROM_VALID_PAGE);

    if (ValidPage == PAGE1)       /* Page1 valid */
    {
        /* New page address where variable will be moved to */
        NewPageAddress = PAGE0_BASE_ADDRESS;

        /* Old page ID where variable will be taken from */
        OldPageId = PAGE1_ID;
    }
    else if (ValidPage == PAGE0)  /* Page0 valid */
    {
        /* New page address  where variable will be moved to */
        NewPageAddress = PAGE1_BASE_ADDRESS;

        /* Old page ID where variable will be taken from */
        OldPageId = PAGE0_ID;
    }
    else
    {
        return NO_VALID_PAGE;       /* No valid Page */
    }

    /* Set the new Page status to RECEIVE_DATA status */
    FlashStatus = FLASH_ProgramHalfWord(NewPageAddress, RECEIVE_DATA);
    /* If program operation was failed, a Flash error code is returned */
    if (FlashStatus != FLASH_COMPLETE)
    {
        return FlashStatus;
    }

    /* Write the variable passed as parameter in the new active page */
    EepromStatus = Flash_VerifyPageFullWriteVariable(VirtAddress, Data);
    /* If program operation was failed, a Flash error code is returned */
    if (EepromStatus != FLASH_COMPLETE)
    {
        return EepromStatus;
    }

    /* Transfer process: transfer variables from old to the new active page */
    for (VarIdx = 0; VarIdx < NB_OF_VAR; VarIdx++)
    {
        if (Flash_GetVirtAddrForId(VarIdx) != VirtAddress)  /* Check each variable except the one passed as parameter */
        {
            /* Read the other last variable updates */
            ReadStatus = Flash_ReadVariable(Flash_GetVirtAddrForId(VarIdx), &DataVar);
            /* In case variable corresponding to the virtual address was found */
            if (ReadStatus != 0x1)
            {
                /* Transfer the variable to the new active page */
                EepromStatus = Flash_VerifyPageFullWriteVariable(Flash_GetVirtAddrForId(VarIdx), DataVar);
                /* If program operation was failed, a Flash error code is returned */
                if (EepromStatus != FLASH_COMPLETE)
                {
                    return EepromStatus;
                }
            }
        }
    }

    /* Erase the old Page: Set old Page status to ERASED status */
    FlashStatus = FLASH_EraseSector(OldPageId, VOLTAGE_RANGE);
    /* If erase operation was failed, a Flash error code is returned */
    if (FlashStatus != FLASH_COMPLETE)
    {
        return FlashStatus;
    }

    /* Set new Page status to VALID_PAGE status */
    FlashStatus = FLASH_ProgramHalfWord(NewPageAddress, VALID_PAGE);
    /* If program operation was failed, a Flash error code is returned */
    if (FlashStatus != FLASH_COMPLETE)
    {
        return FlashStatus;
    }

    /* Return last operation flash status */
    return FlashStatus;
}

/**
  * @}
  */

/******************* (C) COPYRIGHT 2011 STMicroelectronics *****END OF FILE****/
